Adjunct (noun)

1. Something added to another thing but not essential to it.
2. A person or thing that is added to another but is not essential to it.

Origin:

Late latin adjunctus, past participle of adjungere ("to join to"), from ad- ("to") + jungere ("to joi.n")

Examples:

1. He was appointed as an adjunct to the committee.
2. The adjunct to the department helped with the day-to-day operations.
3. The adjunct professor was only teaching one course this semester.
4. The adjunct building was a temporary structure.
5. The adjuncts to the main dish were bread and butter.